7. Nervous Control of Muscular Movement Flashcards

Question

What is Multiple Sclerosis?

Answer 1

Autoimmune disease – body attacks myelin sheath within CNS * Break down in communication * Exposed nerves can be destroyed irreversibly * Fatigue, vision changes, numbness, loss of coordination, muscle weakness, cognitive dysfunction

Answer 2

Synapse – the region where a neuron meets its target cell – axon to dendrite – axon to muscle cell Chemical synapse – electrical signal converted to chemical signal for transmission to the postsynaptic cell

Answer 3

1. Afferent neurons - carry impulses from the sensory receptors into spinal cord or brain 2. Efferent neurons - transmit impulses from the CNS out to the effector organs - muscles (motor neurons) and glands 3. Interneurons - lie entirely within the CNS. They account for 99% of all nerve cells.

Answer 4

The resting membrane potential is the electrical charge difference that exists across the cell membrane of a neuron or other excitable cells when they are not actively transmitting signals. In other words, it's the baseline electrical state of the cell when it's not firing an action potential. In most neurons, the inside of the cell is negatively charged compared to the outside. This charge difference is typically around -70 millivolts (mV) in neurons. This difference in charge is maintained by the movement of ions, such as sodium (Na+), potassium (K+), and chloride (Cl-), through ion channels in the cell membrane. Sodium-potassium pumps also play a role in maintaining this potential by actively transporting sodium ions out of the cell and potassium ions into the cell.

Answer 5

An action potential, also known as a nerve impulse, is a brief electrical signal that travels along the membrane of a neuron. It's a fundamental mechanism by which neurons communicate with each other and transmit information within the nervous system.

Answer 6

Nervous information is relayed across the synaptic cleft by means of a chemical transmitter substance.

Answer 7

Neuromuscular junction - nerve to muscle synapse. The chemical transmitter substance is acetylcholine.

Answer 8

Schwann cells secrete chemical signals required for formation and maintenance of the Neuromuscular Junction

Answer 9

Spatial summation involves simultaneous signals coming from multiple presynaptic neurons being received by a single postsynaptic neuron. Temporal summation involves a single presynaptic neuron rapid-firing signals to a postsynaptic neuron

Answer 10

the chemical transmitter substance is acetylcholine (Ach)

Answer 11

* The spinal cord provide two-way conduction pathway to and from the brain, and it is a major reflex centre. * Paired spinal nerves arise from the spinal cord * 31 pairs of spinal nerves are attached to the spinal cord

Answer 12

31 pairs of spinal nerves are attached to the spinal cord " 8 cervical " 12 thoracic " 5 lumbar " 5 sacral " 1 coccygeal

Answer 13

The cervical enlargement which extends from the C4 through T1 segments of the spinal cord

Answer 14

The lumbosacral enlargement which extends from the T11 through L1 segments of the spinal cord

Answer 15

The lumbosacral enlargement which extends from the T11 through L1 segments of the spinal cord

Answer 16

Plexus – a network of converging and diverging nerve fibers, or blood vessels

Answer 17

The brain and spinal cord are composed of gray matter and white matter. * The nerve cell bodies lie in and constitute the grey matter *axons form the white matter.

Answer 18

Each spinal nerve has a dorsal (back) root and a ventral (front) root connected to the spinal cord. * The dorsal roots contain afferent (sensory) fibers that carry information from the periphery to the spinal cord and brain. * The ventral roots contain efferent (motor) fibers to the skeletal muscle.

Answer 19

Each spinal nerve has a dorsal root and a ventral root connected to the spinal cord. The dorsal roots contain afferent (sensory) fibers that carry information from the periphery to the spinal cord and brain. The ventral roots contain efferent (motor) fibers to the skeletal muscle. The cell bodies of the motor axons making up the ventral roots are located in the ventral gray horns of the spinal cord The cell bodies of the sensory axons making up the dorsal roots are outside of the spinal cord in the spinal ganglia

Answer 20

Ganglion – a collection of nerve cell bodies located outside of the CNS.

Answer 21

* Spinal cord injury is most often the result of trauma to the spinal cord but can also be associated with congenital or degenerative disease. * Every year approximately 10,000 people in the USA survive an acute traumatic injury to the spinal cord. * Causes include – Motor vehicle accidents (36-48%) – Violence (5-29%) – Falls (17-21%) – And recreational activities (7-16%)

Answer 22

The patient is quadriplegic if the cord is transected superior to C5. " If the transection is above C4, the patient may die of respiratory failure.

Answer 23

The patient is paraplegic – paralysis of both lower limbs - if the transection occurs below the cervical segment of the spinal cord.

Answer 24

Proprioceptors Conduct sensory information to the CNS from muscles, tendons, ligaments, and joints

Answer 25

Structure - several modified muscle fibers, 4 to 10 mm in length, contained in a capsule, with a sensory nerve spiralling around its center. Muscle spindles are sensory receptors in muscles that detect changes in muscle length and contribute to our sense of body position. They help regulate muscle tone and coordinate movements by providing feedback to the nervous system.

Answer 26

Muscle spindles are specialized sensory receptors within muscles that detect changes in muscle length and the rate of change. They play a crucial role in reflexes, maintaining muscle tone, and providing sensory feedback for accurate motor control and body position awareness.

Answer 27

Types: – Muscle spindles – change in length – Golgi tendon organ – change in tension – Joint receptors – change in angle

Answer 28

1. Tonic Stretch 2. Phasic Stretch Length 3. Gamma System

Answer 29

Tonic stretch - concerned with the final length of the muscle fibers

Answer 30

Phasic stretch - spindle responds to the velocity of the change of length

Answer 31

Gamma system - gamma efferent fibers When the alpha motor neurons are activated, the gamma motor neurons are also activated (activation). – Gamma system provides the mechanism for maintaining the spindle at peak operation at all muscle lengths. – They help maintain muscle spindle sensitivity

Answer 32

Stretch reflex – e.g. patellar tendon tap automatic response that occurs when a muscle is quickly stretched. When a doctor taps a specific tendon, like the patellar tendon just below the knee, it stretches the quadriceps muscle. This rapid stretch triggers a reflexive contraction of the quadriceps muscle, causing the lower leg to kick forward involuntarily.

Answer 33

Five functional components * Receptor (muscle spindle) * Afferent (sensory) neuron * Integrating Centre (spinal cord) * Efferent (motor) neuron (both alpha and gamma) * Effector (muscle contraction)

Answer 34

In summary, Golgi tendon organs are sensory receptors that monitor muscle tension and contribute to maintaining safe levels of force during muscle contractions, helping to prevent injury and regulate muscle activity. They are in series with the muscle fibers rather than in parallel as are muscle spindles. * When a muscle contracts, the GTO is stretched.

Answer 35

Functions - the firing rate of the GTO is very sensitive to changes in the tension of the muscle. 1. Sensory input from GTO about the tension produced by muscles is useful for a variety of motor acts, such as maintaining a steady gripn on an object. 2. When stimulated by excessive tension or stretch -> send sensory information to the CNS -> causes the contracted muscle to relax (reflex inhibition) – protect the muscle and its connective tissue harness from damage due to excessive loads

Answer 36

Supply information to the CNS concerning * joint angle, * acceleration of the joint * pressure and * pain

Answer 37

The cerebral cortex and cerebellum are the main centers employed in learning new motor skills. These areas of the brain initiate voluntary control of movement patterns.

Answer 38

The cerebral cortex (gray matter), is your brain's outermost layer (3 to 4 mm thick) and lies on top of your cerebrum. The cerebrum is the the largest part of the brain and is split down the middle into two cerebral hemispheres. – The right cerebral hemisphere receives sensations from and controls movements on the left side of the body. – The left cerebral hemisphere is concerned with sensations and movements on the right side of the body. The cerebrum is subdivided into lobes named after the bones of the skull that lie over them.

Answer 39

located at the rear of the frontal lobe of the cerebral cortex. * Stimulation of different areas of the primary motor cortex brings about movement in different, specific areas of the body. * Contains the motor homunculus. However, no coordinated movement can be elicited.

Answer 40

The corticospinal tract is a neural pathway that connects the motor cortex of the brain to the spinal cord, enabling voluntary control of muscle movements. It plays a key role in executing precise and coordinated motions, essential for activities like writing and playing instruments.

Answer 41

One of the three higher areas that command the primary motor cortex. * Located on the lateral surface of each cerebral hemisphere in front of the primary motor cortex.

Answer 42

Somatosensory Cortex * The site for initial cortical processing of pressure, touch, heat pain and proprioceptive input * Located in the anterior section of the parietal lobe, immediately behind the central sulcus. * Each region within the somatosensory cortex receives sensory input from a specific area of the body.

Answer 43

The cerebellum is a part of the brain located at the back of the skull, beneath the cerebrum. Its primary function is to control and coordinate voluntary movements, balance, posture, and fine motor skills. It receives input from sensory systems, the spinal cord, and other parts of the brain to help ensure smooth and accurate movements. Additionally, the cerebellum is involved in motor learning and procedural memory, which means it helps us acquire and refine skills over time through repetition and practice. While often associated with motor functions, the cerebellum also plays a role in certain cognitive processes, such as attention, language, and emotional regulation.

Answer 44

Cerebellum * Function - the major comparing, evaluating, and integrating center for * postural adjustments, – locomotion, – maintenance of equilibrium, – perceptions of speed of body movement, – and general motor coordination.

Answer 45

Damage to the cerebellum results in impaired motor control. Individuals with severe cerebellar damage cannot start or stop movements quickly or easily. They cannot easily combine the movements of several joints into a single, smooth, coordinated motion.

Answer 46

* They cannot perform movements smoothly * They walk awkwardly with their feet well apart. * difficulty maintaining their balance * They cannot start or stop movements quickly or easily * They cannot easily combine the movements of several joints into a single, smooth, coordinated motion. To move the arm, they must first move the shoulder, then the elbow, and finally the wrist.

7. Nervous Control of Muscular Movement Flashcards

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